Lipids are intricate biomolecules responsible for the building up of biological membranes. Besides this structural function, they also display crucial roles in signaling, acting as second messengers that activate specific pathways. Mitochondria are fundamental for cells as they participate in several pivotal functions, such as ATP synthesis, cell survival, metabolic pathways, and calcium homeostasis. Thus, the lipid composition of mitochondrial membranes can affect specific proteins and impact vital functions of mitochondria, such as oxidative phosphorylation and dynamics. The liver possesses a critical function in lipid homeostasis, involving the generation, oxidation, and trafficking of free fatty acids (FFA), triglycerides (TG), cholesterol, and bile acids (BAs). Mitochondria play a key role in lipid storage regulation in hepatocytes, which can control liver function. Their diverse tasks are affected by the lipid composition of mitochondrial membranes, characterized by low cholesterol content and enrichment of specific lipids such as cardiolipin. As mitochondria determine the bioenergetic status of cells and are key regulators of cell viability, alterations of mitochondrial lipid composition can contribute to the induction and progression of chronic diseases, including alcohol-related liver disease (ARLD) and metabolic dysfunction-associated steatotic liver disease (MASLD), two of the most common forms of liver diseases characterized by steatosis, necroinflammation, and fibrosis, which can progress to hepatocellular carcinoma (HCC). Thus, the disruption of lipid metabolism and membrane composition of mitochondria are characteristic features of cancer cells, and altered mitochondrial lipid composition may be a critical player in the progression of chronic liver diseases toward HCC. This review will address the mechanisms whereby alterations of mitochondrial lipid composition lead to the onset and progression of chronic liver diseases. Thus, a better characterization of the alterations of lipid composition in mitochondria may be a crucial step to design strategies and novel therapeutic opportunities for the treatment of MASLD and ARLD.

Hepatocellular carcinoma (HCC) is the most common type of liver cancer and its death rate is rising faster than that of any other cancer, while we still lack effective treatments. The increasing incidence of liver cancer in western countries is closely associated with the growing prevalence of metabolic dysfunction-associated steatohepatitis (MASH) linked to metabolic diseases. While the contribution of lipids in the progression of MASH pathogenesis and its progression to HCC is well recognized, the specific contribution of cholesterol is subject to controversy. The liver plays a central role in cholesterol metabolism, where the majority of its biosynthesis, storage, excretion, recycling, and conversion into bile acids occur. Moreover, cholesterol is implicated in numerous hepatocyte cellular processes, encompassing endoplasmic reticulum function, formation of lipid microdomains in the plasma membrane, metabolism of lipoproteins, and mitochondrial function and performance. Therefore, it is not surprising that cholesterol plays key roles in initiation, promotion, and survival of HCC cells and there are several lines of evidence pointing to that cancer cells are subverting cholesterol metabolism to foster their proliferation and survival through various mechanisms. This narrative review provides a concise overview of the physiological and pathological roles of cholesterol in the transition from healthy hepatocytes to HCC, in the context of MASH. Gaining further understanding of how hepatic cancer cells disrupt cholesterol homeostasis and how these perturbations impact cancer progression will facilitate the identification of novel and more effective cancer treatment strategies in this complex and devastating disease.

The liver, characterized by a unique metabolic and immunosuppressive environment, is also the organ to which invasive malignant cells of many different cancer types most frequently metastasize. The reasons for this organ-specific metastatic process have been investigated for decades. This review first provides an overview of recent breakthroughs in this field, introducing intercellular communication between circulating tumor cells and the heterogeneous cell populations of the liver, and modifications to the extracellular matrix (ECM). Subsequently, to improve the understanding of the molecular mechanisms involved in the metastasis of colorectal cancer to the liver, the second leading cause of cancer-related mortality, the recent literature on this question was analyzed. Among the various parameters involved, the mechanisms behind the activation of hepatic stellate cells, proteins inducing ECM remodeling, specific genomic features of liver metastases, metabolic rewiring, and characteristics of stromal-enriched microenvironments were discussed. To provide more insights into the molecular determinants of liver metastatic colonization, important findings reported on a set of mitochondrial proteins were addressed, the relative abundance of which changed in the liver during the progression stage of an aggressive experimental model of peritoneal malignant mesothelioma in immunocompetent rats. Based on previous studies cross-comparing the liver proteomes from curcumin-treated tumor-bearing rats/untreated tumor-bearing rats/normal rats, data from the literature were reviewed for 25 mitochondrial proteins of interest. Their role in lipid metabolism, heme biosynthesis, the electron transport chain, small molecule transport, mitochondrial dynamics, the tricarboxylic acid cycle, and protection against oxidative stress were analyzed in the context of both cancer and non-malignant liver diseases.

Mitochondria are present in all mammalian cells except matured red blood cells. Mitochondria consist of several metabolic pathways for glucose, fatty acids, amino acids, and bioenergetic pathways for ATP synthesis, membrane potential, and reactive oxygen production. In the liver, hepatic mitochondria play a key role in hepatic steatosis because mitochondrial metabolism produces acetyl-CoA which is the building block for synthesis of lipids and cholesterol. Mitochondria inner membrane is impermeable of metabolites, reducing equivalents, and small molecules such as phosphate, and sulfate. Thus, mitochondrial shuttles and carriers function as the routes of influx and efflux of these metabolites and molecules across the inner membrane. The signal regulation of these shuttles and mitochondrial enzymes could play a key role in coordinating the mitochondrial metabolism to adapt the cytosolic part of metabolic pathways in liver metabolic stress. Intriguingly, the interaction of mitochondria protein SH3 domain-binding protein 5 (SAB/SH3BP5) and c-Jun N-terminal kinase (JNK) was found as a pivotal role in sustained activation of JNK and phosphorylated-JNK (P-JNK) mediated activation of lipogenic pathway in nutritional excess. Knockout or knockdown of SAB prevented or reversed the hepatic steatosis, inflammation, and fibrosis, and improved metabolic intolerance and energy expenditure. Moreover, blocking the SAB peptide prevents palmitic acid-induced P-JNK interaction with SAB and inhibition of mitochondrial bioenergetics, implying the P-JNK effect on mitochondrial metabolism. This review focuses on the flow of mitochondrial metabolites in metabolic stress conditions and the contribution of mitochondria and mitochondrial stress signals in hepatic steatosis.